Interpretive Summary: Biopolymers have potential advantages compared with synthetic petroleum polymers due to their biodegradable properties and, in many cases, lower cost. Annually, the United States produces about one billion pounds of soybean oils in excess of current commercial demand. This excess capacity has resulted in lower prices for soybean oils as well as other agricultural commodities. In this paper, we report the properties of a newly developed soybean oil based material. By studying some of the physical properties of this soybean oil based material and comparing these properties with some other synthetic rubbers, we found out that this newly developed soybean oil based composite has similar properties to those of commercial synthetic rubbers. This biomaterial has potential as a replacement for some of the current commercial synthetic rubbers and/or plastics.

Technical Abstract:
Scientists are more and more interested in biodegradable materials due to their advantage for environment. We investigated viscoelastic properties of a newly developed biomaterial made by epoxidized soybean oil (ESO). ESO cross-linked by triethylene glycol diamine exhibited viscoelastic solid properties. The storage moduli (G') was 2x10**4 Pa over four frequency decades. The phase shifts were 14-18 degrees. Stress relaxation measurements showed that there was no relaxation up to 500 seconds. From plateau modulus we estimated that the molecular weight of this cross-linked soybean oil was in the order of 10**5. The composites of cross-linked ESO with three different fibers had 50 times higher elasticity (G') than that without fiber. Phase shifts were the same as cross-linked oil without fibers. But the linear range of rheological properties was much narrower than that of the material without fibers. All of these results indicated that this new biopolymer made with soybean oil exhibited strong viscoelastic solid properties similar to synthetic rubbers. These rheological properties implied that this biomaterial has high potential to replace some of the synthetic rubbers and/or plastics.